Sorry that I haven't reply yesterday, but the EURO match was too exciting:).
Soooo... from one side I agree that 16oz is a a bit little, however she doesn't seem concerned if after whole night she takes 3oz
If she took 16oz during day and was hungry at 3am I would say - yes do everything to increase intake. Secondly I just remember that DS had periods like that with lower appetite (however he normally took around 25-26oz of milk + 3 solids, so when he was droping to 18oz it was still fine). What worked for me those days was cutting solids to 2 meals or... resigning from cereal for breakfast. When his appetite was fine he was eating 1-2 tbs of cereal for breakfast on milk with fruits. When his appetite was low, this portion made him full for next 6h so I usually gave him 1-2tbs of pure fruir puree or just nothing. I know that most of the BW here would cut the dinner, but I was going with the reco read in some book that dinner is needed to STTN and breakfast should be the last meal to introduce.
Re milk intake - we talk about time and routine... I wonder what about teat flow and temperature of milk. I don't know how hot it's now in Ontario, but if it's hot maybe try to prepare chiller milk? OR change teat-flow for a faster one? Maybe after sometime she is bored with feeding and on the other hand she could deal with a faster flow so she could gulp more? WDYT?